Framing Mechanism For Time-Division-Duplex OFDM Communication Systems

Abstract

The present disclosure outlines mechanisms, systems, methods, techniques and devices that reposition a RMC symbol in a TDD frame. In one aspect, a method queues data transmission units (DTUs) for transmission in a TDD OFDM communication system, with each of the DTUs occupying a single symbol partially or fully, or multiple symbols, of a series of symbols in a TDD frame. The method also forms a management symbol for transmission in a k th symbol position of the series of symbol positions, k>1. The method further transmits the symbols sequentially in the TDD frame.

What is claimed is: 
     
         1 . A method, comprising:
 queuing data transmission units (DTUs) for transmission in a time-division-duplex (TDD) orthogonal frequency-division multiplexing (OFDM) communication system, each of the DTUs occupying a single symbol partially or fully, or multiple symbols fully, or multiple symbols including one symbol partially, of a series of symbols in either a downstream direction or an upstream direction in a TDD frame;   determining a value k, k>1, of the symbol position for a management symbol based on the constraints of:
 a processing time including a time related to one or more of at least DTU processing, fast Fourier transform (FFT), frequency domain equalization (FEQ), forward-error-correction (FEC) code decoding and a time to generate the acknowledgement information for retransmission; and 
 a retransmission buffer size in order to optimize at least one of a retransmission latency and a payload throughput, wherein a value of k is non-unique and different for the downstream direction and the upstream direction; 
   forming the management symbol containing acknowledgement information for retransmission for transmission in the k th  symbol position of the series of symbols; and   transmitting the symbols sequentially in the TDD frame.   
     
     
         2 . The method of  claim 1 , further comprising:
 adjusting the value k of the symbol position for the management symbol based on at least one of the following constraints changes: retransmission latency and retransmission buffer size.   
     
     
         3 . The method of  claim 1 , wherein the TDD frame comprises a group of contiguous OFDM symbols transmitted in a downstream direction following or followed by a group of contiguous OFDM symbols transmitted in an upstream direction. 
     
     
         4 . The method of  claim 1 , wherein the TDD frame further comprises a time gap between the group of contiguous OFDM symbols transmitted in one direction and the group of contiguous OFDM symbols transmitted in the other direction. 
     
     
         5 . The method of  claim 1 , wherein the management symbol contains acknowledgement information for retransmission, configuration information for a physical medium dependent (PMD) layer, or both. 
     
     
         6 . The method of  claim 5 , wherein the configuration information for PMD layer comprises information related to forward error correction (FEC), bit-loading for a transmitter, bit-loading for a receiver, or any combination thereof. 
     
     
         7 . The method of  claim 1 , wherein the management symbol occupies a single symbol. 
     
     
         8 . The method of  claim 1 , wherein the management symbol comprises a dedicated OFDM symbol that is shared with one or more DTUs. 
     
     
         9 . The method of  claim 1 , wherein the transmitting comprises transmitting the management symbol in either or both of a downstream direction and an upstream direction once per TDD frame. 
     
     
         10 . The method of  claim 1 , wherein the transmitting comprises transmitting the management symbol in the k th  symbol position in either or both of a downstream direction and an upstream direction in the TDD frame. 
     
     
         11 . A communication device, comprising:
 a memory unit configured to store data and one or more sets of instructions; and   a processing unit coupled to access the memory unit, the processing unit configured to execute the one or more sets of instructions to perform operations comprising:
 queuing data transmission units (DTUs) for transmission in a time-division-duplex (TDD) orthogonal frequency-division multiplexing (OFDM) communication system, each of the DTUs occupying a single symbol partially or fully, or multiple symbols fully, or multiple symbols including one symbol partially, of a series of symbols in either a downstream direction or an upstream direction in a TDD frame; 
 determining a value k, k>1, of a symbol position for a management symbol based on the constraints of:
 a processing time including a time related to one or more of at least DTU processing, fast Fourier transform (FFT), frequency domain equalization (FEQ), forward-error-correction (FEC) code decoding and a time to generate the acknowledgement information for retransmission; and 
 a retransmission buffer size in order to optimize at least one of a retransmission latency and a payload throughput, wherein a value of k is non-unique and different for the downstream direction and the upstream direction; 
 
 forming the management symbol containing acknowledgement information for retransmission for transmission in a k th  symbol position of the series of symbols; and 
 transmitting the symbols sequentially in the TDD frame. 
   
     
     
         12 . The communication device of  claim 11 , further comprising:
 adjusting the value k of the symbol position for the management symbol based on at least one of the following constraints changes: retransmission latency and retransmission buffer size.   
     
     
         13 . The communication device of  claim 11 , wherein the TDD frame comprises a group of contiguous OFDM symbols transmitted in a downstream direction following or followed by a group of contiguous OFDM symbols transmitted in an upstream direction. 
     
     
         14 . The communication device of  claim 11 , wherein the TDD frame further comprises a time gap between the group of contiguous OFDM symbols transmitted in one direction and the group of contiguous OFDM symbols transmitted in the other direction. 
     
     
         15 . The communication device of  claim 11 , wherein the management symbol contains acknowledgement information for retransmission, configuration information for a physical medium dependent (PMD) layer, or both. 
     
     
         16 . The communication device of  claim 15 , wherein the configuration information for PMD layer comprises information related to forward error correction (FEC), bit-loading for a transmitter, bit-loading for a receiver, or any combination thereof. 
     
     
         17 . The communication device of  claim 11 , wherein the management symbol occupies a single symbol. 
     
     
         18 . The communication device of  claim 11 , wherein the management symbol comprises a dedicated OFDM symbol that is shared with one or more DTUs. 
     
     
         19 . The communication device of  claim 11 , wherein the transmitting comprises transmitting the management symbol in either or both of a downstream direction and an upstream direction once per TDD frame. 
     
     
         20 . The communication device of  claim 11 , wherein the transmitting comprises transmitting the management symbol in the k th  symbol position in either or both of a downstream direction and an upstream direction in the TDD frame.